# Pyrogram - Telegram MTProto API Client Library for Python
# Copyright (C) 2017-2019 Dan Tès <https://github.com/delivrance>
#
# This file is part of Pyrogram.
#
# Pyrogram is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Pyrogram is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Pyrogram.  If not, see <http://www.gnu.org/licenses/>.

import logging

log = logging.getLogger(__name__)

try:
    import tgcrypto

    log.info("Using TgCrypto")


    class AES:
        @classmethod
        def ige256_encrypt(cls, data: bytes, key: bytes, iv: bytes) -> bytes:
            return tgcrypto.ige256_encrypt(data, key, iv)

        @classmethod
        def ige256_decrypt(cls, data: bytes, key: bytes, iv: bytes) -> bytes:
            return tgcrypto.ige256_decrypt(data, key, iv)

        @staticmethod
        def ctr256_encrypt(data: bytes, key: bytes, iv: bytearray, state: bytearray = None) -> bytes:
            return tgcrypto.ctr256_encrypt(data, key, iv, state or bytearray(1))

        @staticmethod
        def ctr256_decrypt(data: bytes, key: bytes, iv: bytearray, state: bytearray = None) -> bytes:
            return tgcrypto.ctr256_decrypt(data, key, iv, state or bytearray(1))

        @staticmethod
        def xor(a: bytes, b: bytes) -> bytes:
            return int.to_bytes(
                int.from_bytes(a, "big") ^ int.from_bytes(b, "big"),
                len(a),
                "big",
            )
except ImportError:
    import pyaes

    log.warning(
        "TgCrypto is missing! "
        "Pyrogram will work the same, but at a much slower speed. "
        "More info: https://docs.pyrogram.org/topics/tgcrypto"
    )


    class AES:
        @classmethod
        def ige256_encrypt(cls, data: bytes, key: bytes, iv: bytes) -> bytes:
            return cls.ige(data, key, iv, True)

        @classmethod
        def ige256_decrypt(cls, data: bytes, key: bytes, iv: bytes) -> bytes:
            return cls.ige(data, key, iv, False)

        @classmethod
        def ctr256_encrypt(cls, data: bytes, key: bytes, iv: bytearray, state: bytearray = None) -> bytes:
            return cls.ctr(data, key, iv, state or bytearray(1))

        @classmethod
        def ctr256_decrypt(cls, data: bytes, key: bytes, iv: bytearray, state: bytearray = None) -> bytes:
            return cls.ctr(data, key, iv, state or bytearray(1))

        @staticmethod
        def xor(a: bytes, b: bytes) -> bytes:
            return int.to_bytes(
                int.from_bytes(a, "big") ^ int.from_bytes(b, "big"),
                len(a),
                "big",
            )

        @classmethod
        def ige(cls, data: bytes, key: bytes, iv: bytes, encrypt: bool) -> bytes:
            cipher = pyaes.AES(key)

            iv_1 = iv[:16]
            iv_2 = iv[16:]

            data = [data[i: i + 16] for i in range(0, len(data), 16)]

            if encrypt:
                for i, chunk in enumerate(data):
                    iv_1 = data[i] = cls.xor(cipher.encrypt(cls.xor(chunk, iv_1)), iv_2)
                    iv_2 = chunk
            else:
                for i, chunk in enumerate(data):
                    iv_2 = data[i] = cls.xor(cipher.decrypt(cls.xor(chunk, iv_2)), iv_1)
                    iv_1 = chunk

            return b"".join(data)

        @classmethod
        def ctr(cls, data: bytes, key: bytes, iv: bytearray, state: bytearray) -> bytes:
            cipher = pyaes.AES(key)

            out = bytearray(data)
            chunk = cipher.encrypt(iv)

            for i in range(0, len(data), 16):
                for j in range(0, min(len(data) - i, 16)):
                    out[i + j] ^= chunk[state[0]]

                    state[0] += 1

                    if state[0] >= 16:
                        state[0] = 0

                    if state[0] == 0:
                        for k in range(15, -1, -1):
                            try:
                                iv[k] += 1
                                break
                            except ValueError:
                                iv[k] = 0

                        chunk = cipher.encrypt(iv)

            return out